Metrology grade light weight tripod

ABSTRACT

A tripod and a method of stabilizing a collapsible stand are provided. The tripod includes three legs attached to a base that swing open to a predetermined angle against a positive stop. The legs are locked into place in the open position via a leg spreader that forces (or pre-stresses/pre-loads) the legs outward against the stops. The method includes the steps of pivoting the legs of the collapsible stand to an open pivotal position into engagement with a stop, applying a load upon the legs to force the legs against the stop, and maintaining the load upon the legs while the stand is in use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority pursuant to 35 U.S.C. 119(e) toco-pending U.S. Provisional Patent Application Ser. No. 61/163,434,filed Mar. 25, 2009, the entire disclosure of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to a stand for various pieces of measuringequipment. More particularly, the present invention relates to alight-weight, rigid tripod for measuring equipment and to a method ofstabilizing a stand (such as a tripod) for measuring equipment.

BACKGROUND OF THE INVENTION

Various industries require precise and accurate measuring for a numberof applications, such as production, manufacturing and process control.In many such applications measurement errors on the order of even onethousandth of an inch can be critical. Thus, it is important that themeasuring equipment being used be stably supported. To provide suchstable support, a stand or tripod is often used. Such stands or tripodsare typically rather bulky and heavy to provide the rigidity necessaryto support the measuring equipment. Therefore, it would be beneficial toprovide a stand for measuring equipment that is light weight and/or lessbulky than conventional stands.

SUMMARY OF THE INVENTION

An object of the instant invention is to provide an improved stand formeasuring equipment. Another object of the instant invention is toprovide a stand for measuring equipment that is light weight. Stillanother object of the instant invention is to provide a stand formeasuring equipment that is collapsible. Yet another object of theinstant invention is to provide a stand for measuring equipment that isless bulky than conventional stands. Still another object of the instantinvention is to provide a method for stabilizing a collapsible stand formeasuring equipment during use.

The above objects of the instant invention are accomplished through theuse of a collapsible tripod that includes three legs attached to a basethat swing open to a predetermined angle against a positive stop. Thelegs are locked into place in the open position via a leg spreader thatforces (or pre-stresses/pre-loads) the legs outward against the stops.

In one embodiment, the leg spreader comprises a member that isadjustably mounted to the base. In another embodiment, the leg spreadercomprises leg-to-leg cross braces that are adjustably mounted betweeneach of the legs of the tripod. In still another embodiment, the legspreader comprises both a member that is adjustably mounted to the baseand leg-to-log cross braces that are adjustably mounted between each ofthe legs of the tripod.

In other embodiments of the instant invention, optional accessories maybe installed on or included with the tripod. Exemplary accessoriesinclude, but are not limited to, padded feet for each leg, pointed feetfor each leg, wheels for each leg, combination wheels and pads/pointsfor each leg (in which the pad/point extends upward and downward fromthe bottom of the leg to either utilize the wheel when the pad/point isup or the pad/point when the pad/point is down), laptop shelf attachedto the base, or levels, and carrying cases. Embodiments of the instantinvention further include a standard thread mount on the top of the basefor mounting measurement instruments and other adapters.

In other preferred embodiments, the legs of the tripod of the instantinvention are extendible and retractable to allow for height adjustment.In some such embodiments, the legs are locked into a desired heightposition utilizing a cam style lever locking mechanism. In still furthersuch embodiments, index marks are included on the legs to provide visualguides when adjusting leg heights.

In use, the tripod/stand of the instant invention is stored in acollapsed arrangement in which the legs of the stand are pivoted intoward the center of the stand and are generally parallel to oneanother. The method of use of the stand includes the steps of pivotingthe legs of the collapsible stand to an open pivotal position intoengagement with a stop, applying a load upon the legs to force the legsagainst the stop, and maintaining the load upon the legs while the standis in use. The primary intended use of the tripod/stand of the instantinvention is with equipment that requires metrology level stability andstrength. The tripod/stand of the instant invention provides therequired stability and strength while also being light weight andportable. In a preferred embodiment, the tripod/stand of the instantinvention can be adjusted to rigidly hold a device at heights between29-47 inches off the ground, and is easily adjusted for that heightrange. Nevertheless, it will be appreciated that alternative embodimentsof the instant invention include a fixed height, as well as a varyingdegree of alternative adjustable height ranges.

The stand of the instant invention is superior to other stands(comparable in price and weight) on the market because of its ability tobecome an extremely rigid and strong structure, but still remain lightweight.

The foregoing and other objects are intended to be illustrative of theinvention and are not meant in a limiting sense. Many possibleembodiments of the invention may be made and will be readily evidentupon a study of the following specification and accompanying drawingscomprising a part thereof. Various features and subcombinations ofinvention may be employed without reference to other features andsubcombinations. Other objects and advantages of this invention willbecome apparent from the following description taken in connection withthe accompanying drawings, wherein is set forth by way of illustrationand example, an embodiment of this invention and various featuresthereof.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention, illustrative of the best modein which the applicant has contemplated applying the principles, is setforth in the following description and is shown in the drawings and isparticularly and distinctly pointed out and set forth in the appendedclaims.

FIG. 1 is perspective view of a tripod of an embodiment of the instantinvention, showing the tripod in a fully set-up position.

FIG. 2 is a top view of the tripod of FIG. 1, showing the tripod in apartially set-up position with one leg-to-leg cross brace in a storageposition.

FIG. 3 is a front view of the tripod of FIG. 2.

FIG. 4 is a sectional view of the tripod of FIG. 2 taken along line A-Aof FIG. 3.

FIG. 5 is an enlarged partial sectional view of the tripod of FIG. 2taken along line B of FIG. 4.

FIG. 6 is an enlarged partial sectional view of the tripod of FIG. 2taken along line C of FIG. 4.

FIG. 7 is a partially enlarged bottom view of the tripod of FIG. 2.

FIG. 8 is a partially transparent perspective view of the lockingmechanism for the extendible legs of the tripod of FIG. 2.

FIG. 9 is a perspective view of a ball and socket leg-to-leg cross braceconnection of a second embodiment of a tripod of the instant invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

As required, a detailed embodiment of the present invention is disclosedherein; however, it is to be understood that the disclosed embodiment ismerely exemplary of the principles of the invention, which may beembodied in various forms. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a basis for the claims and as a representative basis forteaching one skilled in the art to variously employ the presentinvention in virtually any appropriately detailed structure.

Referring to FIGS. 1-8 various view of a tripod of an embodiment of theinstant invention is shown. Tripod 10 includes top plate (base) 20 andlegs 30, 32 and 34 pivotally connected to base 20. Legs 30, 32 and 34open to a predetermined open pivotal position (angle) by creating apositive stop between each leg and the top plate 20 of the tripod 10. Asis shown, each leg pivots outward from a generally collapsed position inwhich all three legs are stored toward the center of tripod 10 generallyparallel to one another, to a fixed position in which a member 21protruding from the top of the leg abuts a protruding portion 23 of thetop plate 20.

In combination with the positive stop described above, there is a “legspreader” device (member) 25 underneath the top plate 20 that istightened into place once the legs are opened. This adds a slightpreload to the legs to keep them tight against the positive stop. Thetightened spreader member also helps remove any potential play in thetop joints of the leg due to manufacturing tolerances. As is shown inFIG. 7, spreader 25 includes a generally triangular shaped (threepronged) trivet member that connects to the bottom of the top plate 20via a threaded member 26 that extends down from the top plate 20 andthrough a hole in the center of the spreader member 25. A knob 27threads onto the threaded member 26 to hold the spreader member 25 inposition and to raise and lower the spreader member 25 with respect tothe top plate 20. When the legs of the tripod 10 are opened, thespreader member 25 is rotated such that the dog-bone shaped (widened)ends align with an engagement plate (90, 92, 94) at the top of each leg(30, 32, 34 respectively). As the knob 27 is tightened to push thespreader member 25 up toward the top plate 20, the ends of the spreadermember 25 press against the engagement plates (90, 92, 94) and force thelegs (30, 32, 34 respectively) outward (open) into tight engagement ofthe stop discussed above. To close or fold (collapse) the legs inward,the knob 27 is loosened to lower the spreader member 25 such that theends disengage the engagement plates, the spreader member 25 is rotatedsuch that the ends are not aligned with the legs, and the legs arefolded inward around the spreader member 25.

Bracing of the legs is from leg-to-leg creating a “tetrahedron” geometryfor stiffness in the whole structure.

In the embodiment shown in FIGS. 1 through 8, the “leg spreader” furtherincludes leg-to-leg cross bracing that cooperates with the spreadermember 25 discussed above to add rigidity to tripod 10. Nevertheless, itwill be appreciated that in some embodiments, spreader member 25 is usedwithout leg-to-leg cross braces, and in other embodiments, leg-to-legcross bracing is used without the spreader member 25. In the embodimentshown, the Leg-to-leg bracing is designed for slight interference (i.e.each brace, 40, 42 and 44, is designed to be slightly longer than thedistance between each leg to create an additional outward or openingforce on each leg) which causes an additional preload on the legs asthey are flexed into position during the set-up of the stand.

In the embodiment shown, the leg-to-leg cross bracing uses a ball andsocket style connection where the socket (e.g. 60 a and 60 b) at eachend of the cross brace (e.g. 40) can be tightened against the ball (e.g.50 a) located toward the bottom of each leg (e.g. 30 and 34) to form arigid connection from leg (e.g. 30) to leg (e.g. 34). As is shown inFIG. 6, the ball and socket connection includes a coupler (e.g. 70 a)that is threaded onto each end of each cross-brace (e.g. 40). Theend-most portion of the cross brace includes the socket connection (e.g.60 a) for receiving the ball portion (e.g. 50 a toward the bottom or 50b toward the top of each leg) of the connection that is located on eachleg. The coupler (e.g. 70 a) is rotated about the threads to eitherengage or disengage the ball socket connection. When engaged, thecoupler clamps the ball (50 a or 50 b) into the socket (e.g. 60 a) toprovide a rigid point of connection. This unique ball and socket designalso allows for the cross brace (40, 42, 44) to be removed from one sideand folded up (pivoted) in parallel with a leg for storage when thestand is collapsed. In such cases, one end of each brace is removed fromits bracing position (i.e. coupled to the ball mounted toward the bottomof each leg) and pivoted up along the leg to which it is still attachedand connected to a ball mounted toward the top of the leg. For example,as is shown in FIGS. 2 through 7, cross brace 44 is folded up to beparallel with leg 34, such that socket 64 b has been removed from afirst ball 50 a of leg 32 and attached to ball 50 b of leg 34 andremains connected to a first ball 50 a of leg 34. Also, as is shown inFIGS. 2 through 7, cross brace 40 connects legs 34 and 30 such thatsocket 60 a connects to a first ball 50 a of leg 30 and socket 60 bconnects to a second ball 50 a of leg 34. Likewise, cross brace 42connects legs 32 and 30 such that socket 62 a connects a second ball 50a of leg 30 and socket 62 b connects to a second ball 50 a of leg 32. Inthe instant embodiment, balls 50 a are all connected to a knee housing86 discussed below. Nevertheless, it will be appreciated thatalternative locations for balls 50 a as well as balls 50 b (which areconnected to base 20) may be utilized without departing from the spiritand scope of the instant invention.

Legs 30, 32 and 34 extend and retract through the ease of use of a camlever locking mechanism 80. Each of legs 30, 32 and 34 include twopieces that slide within each other. However, when the cam is in itslocked position, the two piece leg becomes rigid because of its designfor three surfaces of contact within the two overlapping tubes. As isshown in FIGS. 6 and 8, the cam lever 82 is located within a “knee”housing 86 that is mounted to the lower end of the upper portion 30 a ofthe leg assembly 30. The upper portion of the leg assembly includes ahollow inner diameter that allows the lower portion 30 b of the legassembly (which has a smaller outer diameter than the inner diameter ofthe upper portion) to slide in and out of the upper portion. A plasticbushing (upper bushing 85) is located toward the top end of the lowerleg portion. The upper bushing is fixedly mounted to the lower legportion such that the lower leg portion and upper bushing slide withinthe upper leg portion as a single unit. A middle bushing 83 and a lowerbushing 81 are mounted at fixed locations (as shown in FIGS. 6 and 8)within knee housing 86 below the end (i.e. outside) of the upper legportion. The lower leg portion slides within the middle and upperbushings. The middle bushing is located at the location of the cam andplunger assembly 84, and the lower bushing is located at the lower endof the housing 86. When the cam lever is rotated to lock the leg, thecam presses the plunger inward against the middle bushing. This inwardforce pushes the middle bushing against the lower leg, forcing the lowerleg in the direction opposite the plunger. This in turn forces thebushing located at the top of the lower leg portion into tightfrictional engagement with the inner surface of the upper leg portion ata point generally opposing the side of the leg in which the plunger islocated. In addition, this forces the lower leg into tight frictionalengagement with the inner surface of the lower bushing at a pointgenerally opposing the side of the leg in which the plunger is located.This results in the three surfaces of contact discussed above.

Referring to FIG. 9, a perspective view of a ball and socket leg-to-legcross brace connection of another alternative embodiment of a tripod ofthe instant invention is shown. The ball and socket connection shown inFIG. 9 includes the same basic components as is shown in FIGS. 1 through8, including ball 150 a that is connected to the housing of a knee 180,which in turn is attached to the upper portion 130 of a leg; socket 160a connected to a cross brace 140; and coupler 170 a to clamp the ball150 a within socket 160 a. In addition, the socket shown in FIG. 9includes ramped surface 161 to aid in positioning socket 160 a aboutball 150 a during setup of the tripod of FIG. 9.

The tripods of the embodiments discussed above provides rigid standsthat are stable and light weight. Typical stands of the embodimentsdiscussed herein weigh 20 lbs or less. Moreover, the stands of thediscussed embodiments are adjustable in height from approx. 29-47 inches(with height adjustments made by extending the length of the legs). Thestands of the preferred embodiments are collapsible, require minimalSet-up time (less than 3 minutes). Furthermore, the use of the cam stylelocking mechanisms provides for ease of use in height adjustments. Theinstant invention allows for movable joints to allow the stand tocollapse but also enables the stand to become rigid when tripod is fullyset-up. The strength and stability of the stands of the embodimentsdiscussed herein is primarily designed to meet metrology instrumentrequirements. Nevertheless, it will be appreciated that alternativefeatures to those discussed herein (i.e. height, weight, stability,etc.), may be provided without departing from the spirit and scope ofthe instant invention.

In the foregoing description, certain terms have been used for brevity,clearness and understanding; but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art, because suchterms are used for descriptive purposes and are intended to be broadlyconstrued. Moreover, the description and illustration of the inventionsis by way of example, and the scope of the inventions is not limited tothe exact details shown or described.

Although the foregoing detailed description of the present invention hasbeen described by reference to an exemplary embodiment, and the bestmode contemplated for carrying out the present invention has been shownand described, it will be understood that certain changes, modificationor variations may be made in embodying the above invention, and in theconstruction thereof, other than those specifically set forth herein,may be achieved by those skilled in the art without departing from thespirit and scope of the invention, and that such changes, modificationor variations are to be considered as being within the overall scope ofthe present invention. Therefore, it is contemplated to cover thepresent invention and any and all changes, modifications, variations, orequivalents that fall with in the true spirit and scope of theunderlying principles disclosed and claimed herein. Consequently, thescope of the present invention is intended to be limited only by theattached claims, all matter contained in the above description and shownin the accompanying drawings shall be interpreted as illustrative andnot in a limiting sense.

Having now described the features, discoveries and principles of theinvention, the manner in which the invention is constructed and used,the characteristics of the construction, and advantageous, new anduseful results obtained; the new and useful structures, devices,elements, arrangements, parts and combinations, are set forth in theappended claims.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

1. A tripod comprising: a base; three legs spaced apart generallyequally and pivotally connected to said base; a stop associated witheach of said legs at an open pivotal position for each of said legs; anda leg spreader associated with each of said legs.
 2. The tripod asclaimed in claim 1 wherein each of said legs pivots from a generallycollapsed position to said open pivotal position.
 3. The tripod asclaimed in claim 2 wherein said three legs are generally parallel to oneanother in said generally collapsed position.
 4. The tripod as claimedin claim 1 wherein said stop defines a maximum outward angle for each ofsaid legs in said open pivotal position.
 5. The tripod as claimed inclaim 4 wherein said stop protrudes from said base.
 6. The tripod asclaimed in claim 5 wherein each of said legs includes an engagementmember protruding from said legs that abuts against said stop when eachof said legs is in said open pivotal position.
 7. The tripod as claimedin claim 1 wherein said leg spreader applies a load upon said legs toforce said legs against said stop.
 8. The tripod as claimed in claim 1wherein said leg spreader is mounted to said base at a location centralto said three legs via an adjustable mount.
 9. The tripod as claimed inclaim 8 wherein said adjustable mount permits movement of said legspreader toward and away from said base.
 10. The tripod as claimed inclaim 9 wherein movement of said leg spreader toward said base iscapable of urging said legs outward toward said open pivotal position,and wherein movement of said leg spreader away from said base allowssaid legs to pivot inward toward a generally collapsed position.
 11. Thetripod as claimed in claim 8 wherein said leg spreader comprises athree-pronged trivet that is rotatably mounted to said base via saidadjustable mount.
 12. The tripod as claimed in claim 8 wherein eachprong of said trivet corresponds to one of said three legs such thatsaid prongs are capable of being rotated into alignment with said legs.13. The tripod as claimed in claim 12 wherein alignment of said prongswith said legs urges said legs outward toward said open pivotalposition, and wherein non-alignment of said prongs with said legs allowssaid legs to pivot inward around said prongs of said leg spreader towarda generally collapsed position.
 14. The tripod as claimed in claim 13wherein said adjustable mount further permits movement of said legspreader toward and away from said base.
 15. The tripod as claimed inclaim 8 wherein said leg spreader further comprises bracing adjustablymounted between each of said legs.
 16. The tripod as claimed in claim 1wherein said leg spreader comprises bracing adjustably mounted betweeneach of said legs.
 17. The tripod as claimed in claim 16 wherein saidbracing is dimensioned to apply a load upon said legs to force said legsagainst said stop when said bracing is adjusted to an engaged positionassociated with said open pivotal position of said legs.
 18. The tripodas claimed in claim 16 wherein said bracing is adjustably mounted to atleast one of said legs via a releasable connection.
 19. The tripod asclaimed in claim 16 wherein said bracing is adjustably mounted to atleast one of said legs via a rotatable connection.
 20. The tripod asclaimed in claim 16 wherein said bracing is adjustably mounted to atleast one of said legs via a ball and socket connection.
 21. The tripodas claimed in claim 20 wherein said ball and socket connection isreleasable and rotatable.
 22. The tripod as claimed in claim 20 whereinsaid ball and socket connection includes a coupler that releasablyclamps a ball portion within a coupler portion of said ball and socketconnection.
 23. The tripod as claimed in claim 22 wherein said couplerportion of said ball and socket connection includes a tapered ramp thataides in the positioning of said ball portion within said couplerportion.
 24. The tripod as claimed in claim 1 wherein said legs areextendable and retractable.
 25. The tripod as claimed in claim 24wherein said legs include a locking mechanism that in a locked positionincludes three surfaces of contact between a upper leg portion and alower leg portion of each leg.
 26. The tripod as claimed in claim 25wherein said locking mechanism comprises: a housing mounted to saidupper leg portion and through which said lower leg portion slides; anupper bushing fixedly mounted to said lower leg portion that slideswithin said upper leg portion; a middle bushing and a lower bushingmounted at fixed locations within said housing and through which saidlower leg portion slides; and a plunger that creates a frictionalengagement force between said upper bushing and said upper leg portion,between said middle bushing and said lower leg portion, and between saidlower bushing and said lower leg portion.
 27. A tripod comprising: abase; three legs spaced apart generally equally and pivotally connectedto said base; a stop associated with each of said legs at an openpivotal position for each of said legs; and a spreader means forapplying a load upon said legs to force said legs against said stop. 28.The tripod as claimed in claim 27 wherein said spreader means comprisesa member mounted to said base via an adjustable mount at a locationcentral to said three legs.
 29. The tripod as claimed in claim 27wherein said spreader means comprises bracing adjustably mounted betweeneach of said legs.
 30. A method of stabilizing a collapsible stand formeasuring equipment during use, the stand including at least three legspivotally connected to a base, said method comprising the steps of:pivoting the legs to an open pivotal position into engagement with astop; applying a load upon said legs to force said legs against saidstop; and maintaining said load upon said legs while the stand is inuse.